Where are you gardening? Different areas have different challenges which might cause this.

I don’t believe/suspect it’s something in the dirt or -maybe- it is but the red yardlong and fortes are just fine. 5 feet over is the red, and 10 feet over are the fortex.

Usually, bad seed = dead seed. It is possible that the seed was diseased, but that is unlikely. Are all of the beans from the same source? Ordinarily I might suspect weather as a factor; but in my experience, the red yardlongs are pickier than most in that regard, so that pretty much rules out weather.

In the South you can have pill bugs can do this kind of thing, coming out at night and nibbling on seedlings. Here, in one of my gardens I have a kind of finch which actually flies in and nips bean seedlings off. I wouldn't have believed it if I hadn't seen it.

If you are in a very wet area, there may be a disease issue going on.

Old seed wouldn't help matters either.

Just short of a soil test, any DIY ad-hoc approaches to see if it's the soil. Just for the helluva it, I too one of my many tomato plants and put one in the very area where I have like 8 beans left.

The only strange thing I can say is literally the reds and fortex are in the same bed and are un-affected. It literally starts and stops on the running span of where only this particular species was planted.